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By Tariq B. Hamid

Deep excavation is commonly associated with construction of different deep below-grade structural elements (e.g., basement walls and slabs, tunnels, retaining walls, tanks, utilities, etc.) Deep Excavation Retaining Systems (DERS) are required when open cuts with safe slopes are not possible. Careful analysis, design, and planning of the DERS are required to provide safe below-grade construction and secure nearby structures from damaging effects that may result from the deep excavation. Selection and design of temporary or permanent DERS (e.g., soldier pile and lagging, sheet piling walls, secant pile walls, tie backs, etc.) can have significant impact on time, cost, and performance. In order to design DERS using conventional methods, it is necessary to obtain shear strength parameters, angle of internal friction (ø), and cohesion (c), of retained soils. Residual shear strength parameters (ø'res, c'res) obtained from drained direct shear tests and triaxial tests on saturated samples have been commonly used in practice for the analysis and design of DERS. However, there are cases where ground water table remains at or below the base of excavation during the design lifetime of DERS. In such cases, the soil above the ground water table is in an unsaturated state. Therefore, it is important to account for the unsaturated conditions of soils in order to optimize the design of DERS. This paper is focused on implementing the basic concepts of unsaturated soils mechanics including matric suction and soils-water characteristic curve (SWCC) to estimate design shear strength parameters of unsaturated soils (i.e., ø°, c', and ø') for the design of a cantilever sheet pile walls, a typical case of study of the DERS. The results of this study indicate that the determination of unsaturated soil strength shear strength parameters is simple. In addition, using unsaturated soil mechanics theories has an outstanding impact on the design of retaining systems.

Jan 1, 2006

By B. H. Moore

Foundation and excavation problems associated with lock construction projects vary widely. Each lock requires a different foundation to respond to a unique geologic setting. The range of heights and founding materials are illustrated thru description of selected structures encountered in the United States. Examples range from 113-ft high John Day Lock on the Columbia River founded on basalt rock to the 17-ft high Lock No. 5 on the Arkansas River floated on a clay foundation. A description of the basic elements of design and construction is presented. Several case histories involving lock design and construction are assessed to aid in recognition of potential problem areas on forthcoming construction. In the past decade there have been many improvements in construction materials and techniques. The application of these new approaches to lock construction is discussed.

Jan 1, 2010

By David C. Lager

While not a new construction technique "top/down" construction is seeing increased use in high rise building construction. Using diaphragm wall, drilled shaft and mining construction techniques, top/down construction enables construction of both the below grade basements and high rise structure simultaneously. To date the top/down method has been used on at least four major building projects in the United States. This paper will review the economic, engineering, construction and schedule issues associated with top/down technology on two projects -Olympia Centre, Chicago, and One Westwood, Los Angeles. Top/Down construction is currently under consideration on several additional projects in the United States.

Jan 1, 1987

By Zia Zafir

Design of the deep foundations for the loads imposed by lateral spread include the estimate of the pressure applied by the liquefied material as well as amount of anticipated displacement. In the absence of a non-liquefiable cover over a liquefiable layer, it is possible to design the foundation system just for the additional pressure applied by the flow slides. On the other hand, if a non-liquefiable layer exists above the liquefied zone, the foundation should be designed for anticipated movements. To completely account for liquefaction and/or lateral spread and their interaction with the deep foundation system, a coupled soil-structure interaction (SSI) analysis should be performed. However, a complete SSI analysis may not be feasible for most of the projects. This paper will present recent advances in analysis techniques and simplified methods to design deep foundations for liquefaction and lateral spreading. In addition, a case history of the Rancho California Bridge in southern California located within 1 km of the active Elsinore fault will be presented. One of the bridge abutments is underlain by potentially liquefiable layers. The pressure applied by the liquefiable layer was estimated to be greater than the shear capacity of the 36-inch CIDH piles designed for the abutment. However, with limited ground improvement and more careful analyses incorporating structural effects of CIDH piles, resulting design and construction resulted in a factor of safety greater than 1 against slope failure. The recommended approach was generally consistent with the recently published, and AASHTO sponsored, NCHRP 12-49 project regarding seismic design guidelines for new bridges and the effects of seismic displacements against bridge foundations.

Jan 1, 2006

By Douglas C. Brunot

Mabey Inc. is providing for the shoring design for the Naples bay Center project, located in Naples, FL. The excavation is approximately 374' long by 164' wide and is 27'-8" deep at the shoring line with a groundwater level six feet below present grade. The project Excavation is for a multi-use facility for residential and retail with underground parking. The shoring design will be incorporated into the foundation walls for the building. Mabey is using its pre-engineered Super Powerbrace Plus (SPP) wales and Mega Struts to support the excavation in two phases. The system design and the design of all the pre-engineered components are by Mabey. The foundation is supported on drilled shafts arranged with the building column grid. The excavation will be completed in two phases to allow for equipment mobilization and operation on a site with limited access. The construction sequence will begin with placement of the drilled shafts. The drilled shafts will also serve as the building columns. After the drilled shafts have cured, 630 AZ24-700 x 45 ft. long sheet piles will be installed. The sheets will be arranged in two phases, divided by a center row of piles. Since de-watering in south Florida is very expensive and often downright impossible prior to placing the seal slab, all the initial foundation and excavation bracing work will be completed with groundwater in situ. The entire excavation will be excavated to 5 ft. below ground surface to allow for the installation of the wale support brackets at 12 ft. on center, welded to the sheet piles. After the support brackets are installed, the SPP hydraulic wales and the Mega Strut hydraulic braces may be installed for both phases. Once the frames and struts are in place, Phase 1 excavation is completed, followed by Phase 2 excavation. The 4-ft. thick seal slab is then placed and cured in the wet. De-watering is now possible with the seal slab in place. Once the excavation is de-watered the leveling slab is placed and cured. The center row of sheet piles is then cut off at the top of leveling slab. With the leveling slab cured, the sheet piles have enough strength to support the excavation without the frames and struts near the ground surface. The permanent sheet piles are then seal welded for water proofing and the foundation walls are cast with the sheet piles. The design is modelled in 3D using REVIT to ensure accuracy of the design. The earth pressures are developed using Coulomb theory as there is a top frame and the frame and sheet pile are flexible and move to develop an active pressure wedge. Earth pressure uniform loads and loads from predicted surcharge are modeled in STAAD to determine load effects on the SPP frames and Mega Struts. Coulomb theory and Mabey’s structural model will be tested through monitoring with Mabey’s LIVEPin system. LIVEPin will be placed in struts for each phase of construction. The LIVEPin results will be calibrated with the structural model to determine actual frames forces and will also determine the actual earth pressures applied to the system from surrounding soil. Mabey has used the LIVEPin system in similar applications and this has helped us determine modelling accuracy.

Jan 1, 2018

By Peter Florian

At 5:50 am on October 1, 1992, the new $800 million Pittsburgh International Airport Midfield Terminal opened its gates to the world after five years of construction and more than 24 years of planning. Despite numerous design changes, this massive project was completed on time and substantially within budget. The importance of this airport to Allegheny County and the Pittsburgh region was recognized 24 years earlier by Allegheny County Commissioners Tom Foerster and the late Leonard Staisey. Staisey and Foerster established a program to acquire land for the "Airport of the Future".

Jan 1, 1993

By S. R. Nandargikar

Construction of open foundations for the Second Thane Creek Bridge was indeed a challenging task. Some major problems were encountered during the construction of foundations for pier No. P22 (S/N), P.6(S) and P.12(S) of this bridge. This paper describes these problems briefly and also highlights how they were solved.

Jan 1, 1996

By Martin Pratt

This paper is an overview of deep foundation engineering in Hong Kong past, present and future. The enormity of the subject compared with the space available makes brevity inevitable. Issues of construction and design are covered and some examples of recent challenging projects are given. The content is aimed at those with an interest in foundations generally, but with limited knowledge of the Hong Kong scene. Reference is made to informative publications for further reading on specific topics.

Jan 1, 2000

By James L. Vinson

Wilbur Smith Associates (WSA) has provided planning, engineering and construction oversight assistance to the Tennessee Department of Transportation (TDOT) for three construction projects intended to widen and improve segments of I-40 and associated interchanges in Knoxville, Tennessee. The projects are within the karst terrain of the Valley and Ridge Province. Subsurface conditions are characterized by an irregular rock surface coupled with differential weathering. Because of the projects? impact to local and interstate motorists, consideration was given to innovative planning, materials and construction practices that could accelerate construction. Two innovative deep foundation measures included rock-socketed pipe piles, which act as both foundations and substructure elements for a bridge?s interior bents, and the first widespread use of rock-socketed drilled shafts as bridge foundations on a TDOT project. The pipe piles were used at a site with significant cavities within the limestone bedrock. This resulted in design verification and constructability difficulties that required delays, but measures were ultimately employed to produce a sound foundation system. Over 110 drilled shafts have been constructed at sites with generally low solution activity. Relative to H-pile footings, which were included as an alternate foundation, they have apparently allowed accelerated construction at a competitive cost.

Jan 1, 2006

By Gary Kuhns

Central Florida is among the fastest growing urban areas in the United States, and its rapid development has required the steady construction of various types of civil engineering works. The karst geologic terrain and variable geotechnical conditions, however, present special challenges to the design and construction of deep foundations. The subsurface profile can be idealized as a surficial layer of Pleistocene sands, underlain by the highly variable Miocene-age Hawthorn Group, consisting of various combinations of sand, silt, clay, phosphate and highly weathered limestone. The Hawthorn Group is underlain by Eocene-age limestone that comprises the Floridan aquifer. Vast networks of solution cavities are present throughout the Eocene limestone, sometimes allowing downward raveling of the overlying soils and the creation of sinkholes. In some cases, the relic sinkholes can be filled with soft compressible organic soils extending to depths greater than 100 feet (30.5 m). Driven piles are frequently employed as a deep foundation alternative, although occasionally cast-in-place piles/shafts have also been used. Piles are often driven for bearing in the weathered limestone within the Hawthorn Group, but are sometimes installed as friction piles in the upper soil and intermediate geomaterials. Dynamic pile testing is routinely performed during pre-construction test pile programs, or during production for quality control and assurance purposes. This paper presents discussions on the design and construction aspects of deep foundations unique to Central Florida subsurface conditions and local practice. Foundation issues such as subsurface variability, soil setup, pile damage, negative skin friction, and sinkhole conditions are discussed with the aid of demonstrative case histories.

Jan 1, 2003

By Douglas W. Christie

Deep foundations in Washington, DC have played a role in the city?s development since the 19th century. Designers of government and commercial buildings sought deep foundations initially to minimize settlement of structures. As the western portion of the National Mall was made by filling in portions of the Potomac River, numerous memorials and monuments on the Mall required deep foundations. In recent years deep foundations have been used to allow underground construction for various reasons. Commercial developers have sought to maximize the use of sites by developing below-grade space for parking to meet code requirements and offset the limits on building heights. Underground museum and gallery space has been constructed to expand public space while preserving open space above grade. Access and security concerns have prompted the design of underground visitor centers rather than above-grade structures.

Jan 1, 2006

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Jan 1, 2000

By Antonio A. Cristóvão, Alexandre Pinto

"Abstract Deep foundations of buildings using driven ductile iron micropiles TRIM solutions, leads to recognized advantages, from technical, schedule and economic points of view. High production rates together with the possibility of using conventional equipment, duly adapted, confer this solution a high versatility.The aim of this paper is to describe the main design criteria adopted for the foundations of the Church ""Nossa Senhora dos Navegantes"" building in Lisbon - Portugal. In addition, results of a full scale load test carried out at site are presented, confirming the adequacy of the solution to the geological and geotechnical scenario, which is characterized by the proximity of the Tagus River Basin as well as the presence of heterogeneous landfill material and alluvial layers of soft clay (muds).1. INTRODUCTION Located on the right bank of the Tagus River, in Lisbon, the new Church building of ""Nossa Senhora dos Navegantes"", patroness of fisherman and navigators, with three or four upper floors, is surrounded by a school and by new residential buildings.The Tagus River basin is known by its alluvial soft soils, achieving, in certain areas, more than 50m meters depth, challenging the construction of new facilities due to the significant unfavorable geotechnical conditions.With a modern an unusual architecture, allusive to the ships used by the Portuguese navigators, the building has a reinforced concrete structure, with one basement and three upper floors. A bell tower with about 40m high, emerging from the structure, marks the landscape with the presence of this religious building (figure 2).For all the reasons previously described, geotechnical engineers play a crucial role on the design of valid foundation solutions, from both technical and economic point of view. Ideally, the solutions adopted should be supported by full scale load tests, performed at site, so that design assumptions could be verified and adjusted on time."

Jan 1, 2014

By Michael W. Oakland

Deer Island is the site of the Massachusetts Water Resources Authority (MWRA) wastewater treatment plant which, when completed in 1999, will serve 43 cities and towns in central eastern Massachusetts. Deer Island is located in the Boston Harbor, as shown on Figure 1. The existing wastewater treatment plant on Deer Island is being upgraded to include secondary treatment to comply with Federal require­ments. The new treatment facilities will process an average of 455 million gallons of sewage per day; total capacity will be about one billion gallons per day. The new treatment facilities will cover virtually the entire island. [ ]

Jan 1, 1994

By Scott A. Walker, Roberto A. Lopez, Lori A. Simpson, David A. Shook

500 Folsom Street is part of the new Transbay neighborhood in San Francisco, which is being redeveloped after the 1989 Loma Prieta Earthquake damaged a freeway viaduct; removal of the viaduct created parcels of land available for development. The development consists of a 42-story residential tower with a six-level basement. The slender, core-only structure was designed using performance-based seismic design. Subsurface conditions include undocumented fill, Dune sand, marsh deposits, sand, and clay, all overlying sloping bedrock of the Franciscan Formation. The building is supported on a 10-foot-thick mat foundation approximately 62 to 72 feet below street grades; clay, sand, and bedrock are all present at mat subgrade. Under a portion of the mat, sand susceptible to liquefaction was present. The variable subgrade conditions and potential for ground failure, along with the depth of mat subgrade below street grade, created a challenge for the design and construction team to solve. The ground below mat subgrade needed to be improved to mitigate the liquefaction potential and provide more uniform support. The areal extent and depth of ground improvement necessary to support the mat with an acceptable amount of deformation was determined. Settlement was analyzed and subgrade moduli were provided for design of the mat, with multiple iterations performed to converge between the geotechnical and structural models. Based on the project schedule and logistics, it was beneficial to work from street grade to improve the ground. In order to target the depths below the mat and minimize wasted effort and materials within the depth of excavation, grids of jet grouting were determined to be the most economical ground improvement method; however, it was challenging to install the columns from 65 feet above the top of the target zone. During installation, QA/QC was performed to check that the jet-grouted columns were installed to the design depth and diameter and developed the design strength.

Jan 1, 2018

Structurally- controlled deep leaching processes have removed vast quantities of carbonate from a substantial portion of the "silica-dolomite" enclosing the 500 copper orebody. Mine drainage subsequently allowed free access of air to the porous environment created and oxidation of sulphides commenced. During the mIne development stage the exothermic and temperature-dependent nature of these hydrolysis reactions resulted in a slow general elevation of ground temperatures. and levels of 90 - lOO°C were attained in restricted moist sulphide-rich areas.With the advent of production and extensive use of explosives, the oxidation processes were locally raised to new levels of activity. Direct interaction of explosives and sulphides in favourable conditions caused temperature rises to above 260 C. Above this point the dry oxidation of sulphides in air was initiated and rapid escalation to the vicinity of 800 C has been known to occur in isolated cases.Ground reactivity is a function of the complex interrelationship of several controlling factors and no simple index exists.Control techniques are presently aimed at prevention of temperature rises in the range 100 -260 C. Inhibition of the rapid dry oxidation processes above 260 C is difllcult and current efforts have met with only partial success.

Jan 1, 1968